Research into the variables affecting purge and trap collection for a portable field trihalomethane testing unit.

Abstract

Abstract Trihalomethanes are a group of chemicals formed when chlorine reacts with naturally occurring organic matter and bromide. The Environmental Protection Agency has recently published the Stage 1 Disinfectants/Disinfectation Byproducts Rule to regulate total trihalomethanes at a maximum allowable annual average level of 80 parts per million. Current methods for trihalomethane testing are costly and slow. They have been primarily used in the imposition of fines. As a result, Sandia National Laboratories has developed a cost-effective portable testing unit to detect volatile organic compounds via purge and trap, gas chromatography, and surface acoustic wave detection. The research discussed in this report investigates some of the variables unique to a portable testing device. We have determined three things. First, environmental air can be used as a substitute for helium as a purging gas. Second, the majority of THM removal occurs during the first five minutes of purging. Third, a metal reservoir can be used as a substitute for glass.